[PEM10-P14] Dependence of polar mesosphere echoes on ionization and turbulence over Syowa in the Antarctic
Keywords:polar mesosphere echoes, PANSY radar
Ionization and turbulence are believed to be the triggering factors for these mesosphere echoes, at least for VHF measurements. Because direct measurements of these two quantities are difficult over Syowa, we have compared the occurence of PANSY mesosphere echoes with the following two quantities as proxies of ionization and turbulence: gravity wave activity estimated using MF radar data and local K-index, respectively. The gravity wave activity is positively correlated with PANSY summer echoes (PMSEs), but shows almost no correlation with PMWEs. On the other hand the K-index and mesosphere echoes clearly indicate the opposite relation: positive correlation in winter and almost none in summer.
Thinking of the facts that gravity wave activity in Antarctic mesospehre shows a significant seasonal variation maximizing in winter [e.g. Dowdy et al., 2007; Yasui et al., 2015] and that background electron density is generally higher in summer, these results suggest:
1 Summer mesosphere is in a state of turbulence wanted, but has enough of ionization.
2 Winter mesosphere is in a state of ionization wanted, but has enough of turbulence
Relations in the case of equinoctial months will be further analyzed and shown together with these summer and winter results.
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